Totally different situations Owlet, totally...Did you read the OP's post in that thread? In that situation he has a baby Macaw locked inside a tiny little coffin of a cage where it can't even open it's wings for 23 hours a day, with only 1 toy, and this tiny cage is kept out on a balcony...In that situation the Macaw's "beak wiping" is due to it's shear boredom, loneliness, and because he is literally trapped inside what is basically a coffin for 23 hours every single day with nothing to do but sit and stare. Literally, not exaggerating...And that Macaw's beak is no doing the normal shedding or growing-out that beaks do, that bird is literally wiping his beak back and forth on his cage bars all day long, every day, to the point that he is tearing the outer surface/layer of his beak off, and it's literally hanging off...
Birds do often play with the bars of the cage, they chew them, they make noise with their beaks on the cage bars, etc. They wipe food off of their beaks onto the cage-bars, and sometimes when they are extremely happy or very excited, they purposely slide their beaks back and forth on the cage bars...this is not at all, in any way, the same as what that person's Macaw is doing...I don't think that poor Macaw could even pluck itself if it wanted to, as it's cage is quite literally too small for him to do it! So in it's case, it is constantly, all day long, every single day wiping it's beak on it's cage-bars as a nervous habit...I mean, judging from what it's already done to it's beak in the short amount of time the OP has had him, he must do it constantly, all day long...it's a very sad and frustrating post to read, I feel horribly for that poor Macaw...
But Lincoln is fine! He's just being a bird that is excited and expressing it!!!